Depression Symptoms May Impact Response to Dietary Intervention for IBS

Anthony O'Connor, MD

Credit: Tallaght University Hospital

New research is calling attention to the importance of understanding the psychological profile of patients with irritable bowel syndrome (IBS), highlighting how symptoms of depression can impact response to dietary intervention.¹

Study results showed anxiety symptoms were common in patients with IBS but did not have a notable impact on disease severity or response to dietary therapies. Depression symptoms were less frequent but appeared to have a significant negative impact on response to dietary intervention.¹

IBS is estimated to affect 5-10% of the global population, with many patients experiencing comorbid anxiety or depression. Dietary modifications have become a mainstay of IBS management to help reduce symptoms and improve bowel habits.²

“Although a large amount of data exists examining the epidemiology and proposed mechanisms of the interaction between IBS and psychological disorders, very little is understood about how this might mediate or moderate response to treatments, which is perhaps the most pertinent question for clinicians,” Anthony O'Connor, MD, clinical lead of the department of gastroenterology at Tallaght University Hospital, and colleagues wrote.¹

To determine the impact of anxiety and depression symptoms on response to dietary interventions for IBS, investigators conducted a prospective cohort study of adult patients diagnosed with IBS with diarrhea (IBS-D) or mixed bowel habits (IBS-M) based on Rome IV criteria who attended initially for British Dietary Association (BDA) advice for IBS from community- or hospital-based referrals to the general gastroenterology clinics at Tallaght University Hospital.¹

IBS symptoms were assessed using the IBS severity scoring system (IBS-SSS). Mild, moderate, and severe symptoms are indicated by scores of 75-174, 175-299, and 300-500, respectively.¹

Investigators also assessed the presence of symptoms compatible with a common mental disorder using the hospital anxiety and depression scale (HADS), a self-rating scale containing 2 subscales measuring symptoms of anxiety (HADS-A) or depression (HADS-D) during the previous week. In the present study, a score ≥ 8 for either HADS-A or HADS-D was considered abnormal.¹

The dietary intervention was delivered in 2 stages. The first was in a group setting and consisted of verbal and written instructions based on BDA/National Institute of Clinical Excellence (NICE)-approved dietary guidance for IBS. Patients were asked to adhere to these instructions and to return for a follow-up 3 months later for IBS-SSS reassessment.¹

If symptoms did not improve after the first stage of dietary advice, patients were invited to receive additional instruction on the low FODMAP diet with a trained dietitian. Participants were instructed to follow the low FODMAP diet strictly for 6 weeks, at which point symptomatic response was assessed and they either returned to their normal diet or entered the reintroduction phase for each FODMAP group.¹

The primary endpoint measure was symptomatic response, defined as a ≥ 50-point decrease in IBS-SSS score, or symptomatic remission, defined as achieving an overall IBS-SSS score < 75, at either of the 2 stages. Key secondary endpoints included the decrease in IBS-SSS score from baseline and differences in response based on HADS-A or HADS-D scores.¹

Between September 25, 2017, and January 27, 2021, 503 patients with IBS were invited to participate in the study, 448 (89.1%) of whom attended for first-line dietary advice and were included in the intention-to-treat analysis. The average age of these participants was 42 (range, 16-85) years and 79% were female. The average IBS-SSS score was 290 (SD 86), 69.9% of participants had HADS-A scores ≥ 8, and 39.3% had HADS-D scores ≥ 8.¹

In total, 347 (77.5%) participants returned their follow-up questionnaire and were included in the per-protocol (PP) analysis. Following BDA/NICE-approved dietary guidance, 202 participants achieved the primary endpoint and were subsequently offered guidance on a low FODMAP diet. Of these, 94 (64.8%) patients attended for instruction on the low FODMAP diet and 84 (89.4%) returned their follow-up questionnaire, 49 of whom achieved the primary endpoint. Overall, 251 (56.0%) patients achieved the primary endpoint at either the first or second stage of the dietary intervention.¹

Baseline IBS-SSS scores were significantly lower in the group with HADS-A < 8 (267 vs 299; P <.01). However, despite the difference in symptom severity at baseline, investigators noted there were no differences in achievement of the primary endpoint based on HADS-A scores:

• ITT: 53.4% vs 62.2% for HADS-A ≥ 8 vs HADS-A < 8; P = .09
• PP: 70.5% vs 76.4% for HADS-A ≥ 8 vs HADS-A < 8; P = .30

Similarly, baseline IBS-SSS scores were significantly lower in the group with HADS-D < 8 (267 vs 324; P <.01). Of note, patients with HADS-D ≥ 8 were significantly less likely to achieve the primary endpoint compared with those with HADS-D < 8:

• ITT: 43.8% vs 64.0%; P <.01
• PP: 60.2% vs 79.5%; P <.01

Investigators outlined multiple limitations to these findings, including the focus on the emotional aspects of anxiety and depression with HADS; the high dropout rate between the first and second stages of dietary advice; the influence of the COVID-19 pandemic; the lack of generalizability to a primary care setting; and potential selection bias.¹

“Our study highlights that understanding the psychological profile of patients may be an important factor in predicting response to dietary interventions, with symptoms of depression being of particular importance,” investigators concluded.¹ “It also emphasizes that dietary treatments remain very useful in the management of IBS, with very acceptable response rates even in the key group of patients with psychological comorbidities, in whom often severe gastrointestinal symptomatology is present.”

References

1. ^{O’Connor A, Gill S, Neary E, et al. Impact of HADS Anxiety and Depression Scores on the Efficacy of Dietary Interventions for Irritable Bowel Syndrome. Alimentary Pharmacology and Therapeutics. https://doi.org/10.1111/apt.18337}
2. ^{Staudacher HM, Black CJ, Teasdale SB, et al. Irritable bowel syndrome and mental health comorbidity - approach to multidisciplinary management. Nat Rev Gastroenterol Hepatol. doi:10.1038/s41575-023-00794-z}